1. Technical Field
The present invention relates to a circuit device, an integrated circuit and a detection device, particularly, to a circuit device, an integrated circuit and a detection device which are used for control of an apparatus which uses a sensor.
2. Related Art
In the related art, a detection device or the like which includes a sensor, a technique has been proposed which supplies electric power to the sensor only at the time of measurement to suppress power consumption. For example, in JP-A-2000-74709, in an electronic water meter which is an example of a detection device, a low power consumption operation is realized by supplying electric power to a sensor only at the time of measurement.
However, in JP-A-2000-74709, the sensor is only intermittently operated, and different circuits are constantly operated. In order to further suppress power consumption, it is desirable that the circuits other than the sensor be intermittently operated. For example, if an amplifier circuit which receives an output signal of the sensor and amplifies the signal and a conversion circuit which converts the output signal of the sensor, in addition to the sensor, are also intermittently operated, it is possible to further suppress power consumption.
In a case where the intermittent operation is performed, as the operation time of the sensor, the amplifier circuit and the conversion circuit becomes short, the power consumption reduction effect becomes high. For example, the operation time can be controlled according to the pulse width of a pulse signal used for control. In this case, as the pulse width becomes small, the control can be performed so as to reduce power consumption.
However, if a pulse signal used for control is generated in a sync design based on a system clock, the frequency of the system clock influences the pulse width of the pulse signal used for control. Further, in consideration of unevenness in manufacturing or the like, it is desirable that the pulse width of the pulse signal used for control can be easily and accurately adjusted in shipping, for example.
Further, when the intermittent operation is performed, a settling time is necessary from the time when the circuits are stopped to the time when the circuits start operation and their outputs are stabilized. At this time, it is desirable that the intermittent operation be performed in consideration of an appropriate settling time according to characteristics of the sensor or the amplifier circuit.